Direct reduced iron (DRI), and specifically HDRI—which is still hot from the metallization process, is used as a charge material in the making of steel. Many direct reduction (DR) plants are located in large steelmaking complexes in which HDRI is used on site in a nearby melter or finisher, such as an electric arc furnace (EAF) or the like. The use of HDRI, at a temperature greater than the ambient temperature, is preferable as compared to the use of DRI, at a temperature equal to or less than the ambient temperature, because the sensible heat of HDRI obviates the need to add additional energy, such as electrical energy in the case of an EAF, at the melter or finisher. In addition, HDRI has a lower moisture content than DRI, which is advantageous. When melting or finishing HDRI as compared to DRI, energy consumption is reduced; in the case of an EAF, electrode consumption is reduced; and productivity and yield are increased. Thus, there is a growing trend to charge HDRI to the melter or finisher, as opposed to DRI.
Typically, a DR plant is located in a large steelmaking complex that includes a meltshop. These steelmakers prefer to use HDRI directly from the DR plant. However, it is often not practical to locate the DR plant directly adjacent to the meltshop (i.e. within about 100 meters). Thus, the HDRI must be charged into the EAF using a hot transport vessel (HTV). In fact, some steelmakers simply prefer this procedure to gravity feeding HDRI into the EAF or using other types of mechanical hot conveyors. Existing HTV procedures are non-optimal for several reasons: 1) the feed rate of the HDRI charged into the EAF may not be accurately controlled; and 2) an EAF charge crane must be used to hold the HTV in position while charging the HDRI into the EAF, thereby limiting the annual volume of HDRI that may be charged into the EAF. Thus, existing HTV procedures are crude “crane-and-dump” procedures.
In all of these HTV procedures, the HTV utilized includes a relatively flat bottom, a plurality of trunions for lifting and turning the HTV, and a conical top including a port that serves as both an inlet and an outlet. Typically, the HTV is on rails. Other suitable transport procedures include mechanical hot conveyors, pneumatic hot conveyors, etc. One exemplary HTV is disclosed in commonly-assigned U.S. Pat. No. 6,214,086 to Montague et al., issued on Apr. 10, 2001, and entitled “Direct Reduced Iron Discharge System and Method.”
What are still needed in the art, however, are methods and apparatuses for charging HDRI from HTVs into a melter or finisher wherein the feed rate of the HDRI charged is known and controllable—by computer, for example; the feed rate of the HDRI charged may be substantially continuous; both heat loss and dust emissions are minimized; re-oxidation is minimized; existing meltshop equipment may be accommodated, such as EAF charge cranes, etc.; both existing and novel HTVs may be accommodated; and other materials may be charged, such as slag formers and reductants. Preferably, these methods and apparatuses would be robust and reliable, and would maximize the annual volume of HDRI that may be charged.